Found fuzz type things on hair and brought samples to the derm, can they determine anything by looking at it under microscope?

Absolutely; yet best: see yourself using their microscope & their help so that you better understand what both you and they are talking about. However, best check to be sure the people you plan to go to have a microscope in their office; many physicians do not keep microscopes in the offices because of the combined cost & little payment for keeping/using them. Seeing will help you better understand & verify quality.

Hair analysis.: I'm not sure about your specific issue, but part of a hair analysis is a microscopic examination of the hair shaft. Perhaps the Dermatologist will see something.